Highway lighting apparatus



p 9, 1 40. M. coHu ML 2,196,548

I HIGHWAY LIGHTING APPARATUS Filed Nov. 19, 1936 3 Sheets-Sheet 1 I//vvE/v7'07? April 9, 1940.

M. COHU El AL HIGHWAY LIGHTING APPARATUS a Sheefs-Sheet 2 Filed Nov. 19,1936 llllll-I'l'll lilllllllll-ll LllIfill-lnll P 1 M. COHU ET ALHIGHWAY LIGHTING APPARATUS 3 Sheets-Sheet 5 Filed' Nov. 1 9, 1956Patented Apr. 9,1940

HIGHWAY LIGHTING APPARATUS Merry cent and Alfred Trequigneaux, ParisFrance, assignors tov Societe' Anonyme ies Ancjens EtablissementsSaunier Duval Frisquet,

Paris,'France, a. company of France I "Application November 19, 1936,Serial No. 111,736 In Fran c v m er25,1935

Claims. (014210-29 The present invention relates to lighting apparatusfor roads, streets and the like.

The object of the invention is to provide an apparatus of this kindwhichpermits of seeing in a. satisfactory mannerduring nighttimeobstacles and o h r objects; present on the. surface of the road,especially v hen said surfaceis Wet. and has a low diffusing power; I Y

The apparatus according to the present inven-.

10' tion consists, on the. one hand, of a light source,

incandescence lamp, gas mantle, low or high pressure dischargeluminescent tube, etc., and, on the other hand, of. reflecting. surfacesintended to dis tribute the light in directions parallel to the axial14$ plane of the roadway -(this expression axial plane is intended tomean a plane, generally a vertical plane, passing through the axis ofthe roadway). These surfaces perform two chief functions; 2 a. .Thecentral mirror structure returns to a great distance thelight fluxemitted bythe lamp, in directions close to the axis of the, road, insuch manner as to create a certain uniformity offil: lum nati n whi halso permits of. obtaining a u i n y niform brilliancy in, the case of aroadway surface that diffuses ina. suitable man-. ner.

mer t, the light flux directed by means of said central surface orsurfaceswillhe limited be.-

tween. two ver ica planes; located on either side of the axialverticaliplane of'the-roadwayand.

making each an angle, of 50.60 with said. axial vertical plane. 1

b. The lateral mirrorelements located oneither side of the centralsurtaces will act uponthe light flux emitted by the lamp in directionstransverse to the axis of the road (as a rule, this fluxisbadly utilizedorremainsv unemployed in many of the apparatus used at the present time)in 'such manner'as to direct this flux. also in'directions substantiallyparallel to, the axis of the road so that these lateralsurfacescorrespondto the ore ation of further bright bands on, thesurf-ace of the roadway. v 1

The central and lateral elements of the mirror consist of reflectinsurfaces such. as, obtained withpolished metals (silver-plated,chromium+ p e c l e d as or pri matic, la s; syn

terns acting either byrefraction or by total res fiection.

The apparatus accord ng to the. resent} invention will have an elon atedshape. inadirection at'right angles to the, axisoi the mad;

They will bearra 'ged stageenedrelatione For i st ce accordin to apreferred embodiship to one another in the transverse direction of theroad in such manner that the wide luminous bandsthey' produce arejuxtaposed.

Other featuresof the present invention will specific embodimentsthereof. 1 Preferred embodiments ofthe present invention will behereinafter described; with referenceto the accompanying drawings, givenmerely by way of example, and in which: I m

1 shows a mirror according to the invention in section by a planeparallel tothe axisof the roadway to be illuminated; I

2 is a section of the, same mirroron the line I I.-I I of Fig. 1, thatis to say in a plane 15 at rightang-les to the axis of the roadway;

3 shows a section of themirror by a horizontal plane containing line.lII-III;

Fig-; {l is a view similar to Fig. 2, showing a modification; no Fig. 5is a section of this modification on the line V-.-V of Fig. 4;

' Fig; G is, a plan view of another modification;

Figs. 7 and 8 are explanatory views illustrating the use. of mirrors.according to the invention for the illumination of a roadway; and I Fig,9- represents a mirror according to the present invention shown inprojection on the vertical plane perpendicular to the axis of thehighway;

In. the, drawings, reference character a desig resultjr n the followingdetailed description oi .nates elements of reflecting surfacesconstituting the central part of the mirror and which includeslowersurfaces a consistingof portions of paraboloids and a sphericalupper surface S, so as to M recuperate an important portionof the flux.The centerof the sphere and the focus of the paraboloids are located ation the light source close to the plane separating surfaces (1, and S"from each other. i v. I ,b is one of the two lateral elements of themirror. Each of these two lateral surfaces, only one of which is shownin' Figs; 2 and 3, is constituted in this example by juxtaposedseparatemirrors 7' of suitable curvature and direction.

In the modification of-Figs4 and 5, the elementary'mirrors whichconstitute the lateral parts li -include each: 1'. a. lower part rconsistingof an element ofv a paraboloid having. its. focus on the lightsource and the; axis: of which is located in the vertical J plane.parallel. to the axis. of the'road passing throu h said source; Y

2,; an upper partr consisting of, a'portion. of a enneia c ne: ofevolution f0 n nce havin surfaces, which are of smaller size.

, various possible positions of the observers.

its apex at c on the axis passing through the light source.

The parabolic lower portion 7 returnsthe light rays parallelly to itsaxis, whereas the upper part 1' ensures a relatively wide dispersion ofthe rethe axis of the roadway. The lateral parts b of the mirror areprovided, at their ends, with a portion of an elliptic mirror e one ofthefocuses of which coincides with the light source located. at f, whilethe other focus is at f1. .Between the portions of paraboloids T havingtheir focus at f as above explained, are provided other portions ofparaboloids is having their focuses at f1 and the axes of which are inthe vertical plane passing through hand parallel to the axis of theroad. The light rays issued from f and striking paraboloids T arereflected as above toward the axis of the road. The light rays that donot strike the paraboloids r strike ellipsoid e and are reflected bypassing through f1, after which they strike paraboloids rs which reflectthem parallelly to the axial plane of the road.

Of course the ellipsoid has been given only as an example of asuitable'reflecting surface arranged so that the focus f of paraboloids1a is placed on the image of the source given by said surface.

The apparatus that have been just described give, by reflection uponroadways which arelittle diifusing or moist, wide bright bands,themselves constituted by the juxtaposition of the bands correspondingto the central and lateral reflecting The width of the apparatus, andtherefore that of the bands, may, by way of example, be about twometers.

In order to obtain a uniformly bright appearance of the roadway, thepresent invention includes a particular arrangement of the apparatuswhich will juxtapose the bright bands for the It will be advantageous,according to the present invention, to abandon the old arrangements ofthe apparatus all in axial or lateral position, and to combine thesearrangements, and also eventually to place said apparatus inintermediate positions between the axis and the sides of the road.

By way of example, Figs. 7 and 8 show "a possible arrangement of theapparatus In these figures we have shown in a diagrammatic manner thelight bands created on a rectilinear and plane road by apparatus F1, F2,F3, F4 as seen by an observer moving along the road. Fig. 7 correspondsto a positionof the observer, and Fig. 8 to another position. It will benoted that, from a 1 certain distance of the observer, the light bandscover the whole area of the road. The crosshatched portionsin Figs. 7and 8 showthe zones that are not covered by luminous bands and for whichthe object, located at a small distance, will be made visible by thecontrasts existing between its own parts. If the visibility of theobjects is considered as insufficient in these zones, it is possible tomake use of apparatus of larger size or to associate several of theseapparatus in such manner that they constitute a continuous line.

As illustrated in Figure 9 the mirror is preferably placed so that itslarger'ax'is is perpendicular to the longitudinal axis of the highway.It may be suspended, for example, by chains 2 from a continuoussourcesformed, for instance, by the juxtaposition of a plurality of lamps ofsmall or mean power. f

In a general manner, while we have, in the above description, disclosedwhat we deem to be practical and efficient embodiments of the presentinvention, it should be well understood that we do not wish to belimited thereto as there mightbe changes made in the arrangement,disposition and form. of the parts without departing from the principleof the present invention as comprehended within the scope of theappended claims. v I

What weclaim is:

1. An. illuminating apparatus for a roadway which comprises, .incombination, a light source and a composite mirror of elongated shapehaving its length at right angles to the axis of the roadway andincluding a central structure comprising at least two reflectingparaboloid mirror surfaces having both of their respective focuses onsaid source and their respective axesin a vertical plane passing throughsaid source and parallel to the. axis of the roadway, said axes beinginclined and passing through the opposite ends, in the direction of theroadway axis, of the field to be illuminated, and twolateral mirrorstrucing its length at right angles to the axis of the roadwayandincluding a central structure comprising at least two reflectingparaboloid mirror surfaces having both of their respective focuses onsaid source and their respective axes inha vertical plane passingthrough said source and parallel'to the axis of said roadway, said axesbeing inclined and passing through the opposite ends, in the directionof the roadway axis, of the field to be illuminated, said centralstructure being limited by two planes passing through said source andmaking an angle of at most with said vertical plane and on either sidethereof, respectively, and two lateral mirror structures located oneither side of said central structure along saline at right angles tosaid vertical plane, each of said lateral mirror structures including aseries of parallel vertical steps arranged to reflect light rays fromsaid source parallelly to said vertical plane.

3. An illuminating apparatus for a roadway surfaces in the form ofportions of paraboloids having their focuses on said source and theirrespective axes parallel to said vertical plane but oblique with respectto a horizontal plane.

4. An illuminating apparatus for a roadway Y which comprises, incombination, a light source and a composite mirror of elongated shapehaving its length at right angles to the axis of theroadway andincluding a central structure which comprises at least two reflectingparaboloid mirror surfaces having both of their respective focuses onsaid source and their respective axes in a vertical plane passingthrough said source and parallel to the axis of said roadway, said axespassing through the opposite ends, in the direction of said roadway, ofthe field to be illuminated, said central structure being limited by twoplanes passing through said source and making with said vertical planeand on either side thereof an angle of at most 60, two lateral mirrorstructures located on either side of said central structure in adirection at right angles" to said vertical plane, and a reflectingsurface at the outer end of each of saidlateral mirror structuresadapted to give animage of said source, said lateral mirror structuresincluding parabolic elementshaving their focuses on said image andadapted to reflect the light rays from said image to aremote point ofsaid roadway,

parallellysto said first mentioned vertical plane.

5. An illuminating system for a roadway which comprisesin combination, aplurality of illuminating apparatus comprising each a light source and acomposite mirror of elongated shape having its length at right angles tothe axis of the roadway and including av central structure comprising atleast two reflecting parabolic mirror surfaces having both of theirrespective focuses on said source and their respective axes in avertical plane passing through said source and parallel to the axis ofthe roadway, said axes passing through opposite ends, in the directionof the roadway axis, of the field to be illuminated, and two lateralmirror structures located on either side of said, central structurealong a line passing throughsaid source and at right angles to saidplane, each ofsaid lateral mirror structures including a series ofparallel vertical steps arranged to reflect light rays from said sourceinto directions parallel to said plane, said plurality of apparatusbeing arranged in staggered relationship on the road in such manner thatthe respective light bands emitted by said apparatusare substantiallyjuxtaposed to one another on the surface of the roadway.

MERRY'COHU.

Q G UX

